User`s guide

filt
11-77
11filt
Purpose Specify discrete transfer functions in DSP format
Syntax sys = filt(num,den)
sys = filt(num,den,Ts)
sys = filt(M)
sys = filt(num,den,'Property1',Value1,...,'PropertyN',ValueN)
sys = filt(num,den,Ts,'Property1',Value1,...,'PropertyN',ValueN)
Description In digital signal processing (DSP), it is customary to write tra nsfer functions
as rational expressions in and to order the numerator and denominator
terms in ascending powers of , for example,
Thefunction
filt is providedto facilitate thespecificationoftransfer functions
in DSP format.
sys = filt(num,den) creates a discrete-time transfer function sys with
numerator(s)
num and denominator(s) den. The sample time is left unspecified
(
sys.Ts = –1)andtheoutputsys is a TF object.
sys = filt(num,den,Ts) further specifies the sample time Ts (in seconds).
sys = filt(M) specifies a static filter with gain matrix M.
Any of the previous syntaxes can be followed by property name/property value
pairs of the form
'Property',Value
Each pair specifies a part icular LTI property of the model, for example, the
input names or the transfer function variable. See “LTI Properties” on page
2-26 and the
set entry for additional information on LTI properties and
admissible property values.
Arguments For SISO transfer functions, num and den are row vectors containing the
numerator and denominator coefficients ordered in ascending powers of .
For example,
den = [1 0.4 2] represents the polynomial .
z
1
–
z
1
–
Hz
1–
()
2z
1
–
+
10.4z
1–
2z
2–
++
---------------------------------------------=
z
1
–
10.4z
1
–
2z
2
–
++